A TRLFS Study on the Complexation of CmIII and EuIII with 2,6‐Bis(5,6‐dipropyl‐1,2,4‐triazin‐3‐yl)pyridine in Water/Methanol Mixture

The complexation of CmIII and EuIII with 2,6‐bis(5,6‐dipropyl‐1,2,4‐triazin‐3‐yl)pyridine (nPr‐BTP) in water/methanol solution is studied. 1:3 complexes [M(nPr‐BTP)3]3+ form from the solvated metal ions upon addition of ligand. The conditional stability constants are log K = 14.4 and log K = 11.9. For both metal ions the complexation reaction is both enthalpy and entropy driven. ΔH is 10.1 kJ/mol more negative than ΔH , whereas the entropy difference is small. The difference in ΔG between the formation of the CmIII and EuIII complexes is in good agreement with nPr‐BTP's selectivity in liquid‐liquid extraction.